In the field of automobiles or the like, for example, a seal member which is disclosed in Patent Literature 1 is known as a seal member (gasket) that is to be interposed between an upstream exhaust pipe and a downstream exhaust pipe. The seal member is interposed between a first flange of the upstream exhaust pipe and a second flange of the downstream exhaust pipe in order to seal the gap between end portions of the upstream and downstream exhaust pipes.
The seal member is configured by using expanded graphite and a metal mesh, and includes a first sealing surface and a second sealing surface. The first sealing surface is configured as a convex spheroidal surface which is to butt slidably against a concave spheroidal sealing surface disposed on the first flange. The second sealing surface is configured as a convex spheroidal surface which is to butt slidably against a concave spheroidal sealing surface disposed on the second flange.
However, the gasket has the configuration where the first and second sealing surfaces having a convex spheroidal shape simply butt against the concave spheroidal sealing surfaces of the corresponding flanges, respectively, and therefore cannot ensure a high sealing property between the first and second flanges. Namely, there is room for improvement in the sealing property of a gasket.